[Intel-gfx] [PATCH] drm/intel: Only smash VGA SR01 register if intel is default VGA device

2013-12-17 Thread Keith Packard
We want to disable the (unused) VGA plane on the intel hardware, which should be a simple matter of writing the vga control register. However, in 2009 (commit 24f119c769bacac5729297b682fec7811a983cc6), that simple code was changed to also smash the SR01 VGA register to fix random crash and

Re: [Intel-gfx] [PATCH] drm/intel: Only smash VGA SR01 register if intel is default VGA device

2013-12-17 Thread Chris Wilson
On Tue, Dec 17, 2013 at 09:12:10AM -0800, Keith Packard wrote: We want to disable the (unused) VGA plane on the intel hardware, which should be a simple matter of writing the vga control register. However, in 2009 (commit 24f119c769bacac5729297b682fec7811a983cc6), that simple code was changed

Re: [Intel-gfx] [PATCH] drm/intel: Only smash VGA SR01 register if intel is default VGA device

2013-12-17 Thread Keith Packard
Chris Wilson ch...@chris-wilson.co.uk writes: The bspec still says we must assert SR01 bit5 prior to disabling the VGA plane. Perhaps the test should be whether (vga_reg VGA_DISP_DISABLE) == 0 and do nothing if the plane is already off. The problem is that for some reason we're smashing

Re: [Intel-gfx] [PATCH] drm/intel: Only smash VGA SR01 register if intel is default VGA device

2013-12-17 Thread Chris Wilson
On Tue, Dec 17, 2013 at 10:17:24AM -0800, Keith Packard wrote: Chris Wilson ch...@chris-wilson.co.uk writes: The bspec still says we must assert SR01 bit5 prior to disabling the VGA plane. Perhaps the test should be whether (vga_reg VGA_DISP_DISABLE) == 0 and do nothing if the plane

Re: [Intel-gfx] [PATCH] drm/intel: Only smash VGA SR01 register if intel is default VGA device

2013-12-17 Thread Keith Packard
Chris Wilson ch...@chris-wilson.co.uk writes: Ok, so as no vgaarb_clients have yet been registered and so the call to grab the IO resource does not actually disable VGA IO routing to the nvidia card. Yikes! This explains a lot. If you care to update the changelog to explain the problem is